ATECC508A datasheet(21/109 Pages) MICROCHIP

21 / 109 page

Bit

Name

Description

0 = The public version of this key can never be generated. Use this mode for the

highest security.

1 = The public version of this key can always be generated.

If Private indicates that this slot does not contain an ECC private key, then this bit may be

used to control validity of public keys. If so configured, the Verify command will only use

a stored public key to verify a signature if it has been validated. The Sign and Info

commands are used to report the validity state. The public key validity feature is ignored

by all other commands and applies only to Slots 8 – 15.

0 = The public key in this slot can be used by the Verify command without being

validated.

1 = The public key in this slot can be used by the Verify command only if the public

key in the slot has been validated. When this slot is written for any reason, the most

significant four bits of byte 0 of block 0 will be set to 0xA to invalidate the slot. The

Verify command can be used to write those bits to 0x5 to validate the slot.

Private

0 = The key slot does not contain an ECC private key and cannot be used with the

Sign, GenKey, ECDH and PrivWrite commands. It may contain an ECC public

key, a SHA key, or data.

1 = The key slot contains an ECC private key and can be used only with the Sign,

GenKey, ECDH and PrivWrite commands.

More information on select fields is described below.

•

Private:

This bit indicates that the slot contains an ECC private key and it is used by the device to limit uses

of this slot to the appropriate ECC commands.

If this bit is set, then SlotConfig.ReadKey is used to enable or disable the use of the private key for

various operations. ReadKey<0> enables the use of the key for signatures of externally supplied

data, while ReadKey<1> enables the use of the key to sign only messages that are stored in

TempKey by the GenKey or GenDig commands. This mechanism permits a remote entity to have

the knowledge that a particular key value or slot contents are stored within an ATECC508A device,

and it prevents an attacker from creating an external message that would model an internal state

that does not exist and create a signature of that state.

•

PubInfo:

For public keys, this field can be used to walk a certificate chain to validate the key. This feature is

implemented using the Verify command and the validation is stored in nonvolatile memory

alongside the key so that subsequent uses of the public key do not require additional validation.

These keys are always invalidated when any part of the slot containing the key is written.

For private keys, this field can be used to increase security or privacy in some situations by

preventing the generation of the public key corresponding to a private key. The presumption is that

the public key has been stored elsewhere at the time the private key was generated or written into

the device. This field is ignored when a random key is generated. The ATECC508A includes a

method of walking either an X.509 certificate chain or a simplified internal format chain. See the

SHA and Verify(ValidateExternal) commands for more details.

ATECC508A

Device Organization

Datasheet Complete

DS20005927A-page 21

ATECC508A Arkusz danych(PDF) 21 Page - Microchip Technology

ATECC508A Arkusz danych(HTML) 21 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Arkusz danych Pobierz

Link URL